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Use of RT plugs 30" od 2.25cr B31.1

Use of RT plugs 30" od 2.25cr B31.1

Use of RT plugs 30" od 2.25cr B31.1

(OP)
I am working on a repair procedure to replace a 2' section of 30" od, 375 wall 2.25 cr pipe. RT required to get by the hydrotest. B31.1

The previous installation had RT plugs installed. Are they nessesary in this application? I would like to not require them if possible. It appears they are not required but makes the RT process a one-shot deal vs having to rotate the camera 3 times. Correct?


The finished product is in a wide open location.

Thank you in advance.

RE: Use of RT plugs 30" od 2.25cr B31.1

Yes, for RT gamma plugs are the norm. You might want to consider ultrasonic examination (UT) for this application. TOFD or shear wave can be used depending on your procedure.

RE: Use of RT plugs 30" od 2.25cr B31.1

We seldom if ever use gamma plugs for pipe welds that thin. We generally require gamma plugs for wall thickness > or = 3/4-inch and diameters > or = 10-inches.  

RE: Use of RT plugs 30" od 2.25cr B31.1

(OP)
Thank you for the comments. Considered using UT in lieu of RT but had concerns of the 1/8" dead zone. The pipe is pretty thin. Agree?

RE: Use of RT plugs 30" od 2.25cr B31.1

A conventional shear wave technique with UT would work on a butt weld of this wall thickness. Check with a nondestructive testing company for specifics.

RE: Use of RT plugs 30" od 2.25cr B31.1

Time of Flight Diffraction or Phased array ultrasonic inspections are both capable of examining these welds.

RE: Use of RT plugs 30" od 2.25cr B31.1

I have not come across "RT plugs" before. I think I understand the (simple) principle of an entry port in the wall of a vessel or pipe for insertion of the gamma-ray guide tube (maybe Gamma plug would be a better description) in order to reduce exposure times (single panoramic possible versus multiple double wall exposures). I have searched this forum and got to the reference to the Pipe Fitting Institute PFI Standard ES-16 - but I dont have a copy. Can anyone direct me to any further technical information. Would be grateful.

Nigel Armstrong
Karachaganak Petroleum
Kazakhstan

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